opencv库安装
方法1：
sudo apt-get install libopencv-dev（编译好的二进制库和头文件）
安装位置：
头文件：/usr/local/include/opencv2/
库文件：/usr/local/lib/
方法2：
官网直接下载源码，编译安装：https://opencv.org/releases/page/3/，如下载3.4.6-Sources；
*.zip文件解压指令：unzip
*.tar.gz文件解压指令：tar -xzvf
解压成功得到opencv-3.4.6文件夹，cd opencv-3.4.6，mkdir build，cd build，cmake …
此时还没结束，还需要make！！否则在使用时会报错：
CMake Error at CMakeLists.txt:3 (find_package):
By not providing "FindOpenCV.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "OpenCV", but
CMake did not find one.
Could not find a package configuration file provided by "OpenCV" with any
of the following names:
OpenCVConfig.cmake
opencv-config.cmake
此时生成文件在build文件夹里面，但编译还没有结束！！还需要sudo make install！！，该功能有点类似将build下面的库和头文件安装到/usr/local/lilb和/usr/local/include下面。
测试demo有个注意事项：
–CMakeLists.txt
–main.cpp
–1.bmp
–build
----opencv_demo
注意，在新建build， cmake…，make后，生成的opencv_demo要拿到外面来，因为main.cpp中写的cv::imread("./1.bmp")的图片是相对路径，若不想拿到外面来只需将其换成绝对路径。
bug:
此时无法用cv::imshow
zzz@ubuntu:~/zzz/sl/mine/ch5_opencv/build$ ./opencv_demo
terminate called after throwing an instance of ‘cv::Exception’
what(): OpenCV(3.4.6) /home/zzz/zzz/software/opencv-3.4.6/modules/highgui/src/window.cpp:634: error: (-2:Unspecified error) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Carbon support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script in function ‘cvShowImage’
解决办法：
apt-get install libgtk2.0-dev pkg-config
安装成功之后，重新使用cmake对opencv源码进行编译，安装。
CMakeLists.txt demo:
cmake_minimum_required( VERSION 2.8)
project(opencv_demo)
find_package( OpenCV REQUIRED )
# 如果有多个版本，需要指定以下版本号。若只有一个，则不用加，如上面一句话
# find_package( OpenCV 3.4 REQUIRED )
# find_package( OpenCV 2.6 REQUIRED )
include_directories( ${
OpenCV_INCLUDE_DIRS} )
add_executable( opencv_demo main.cpp)
target_link_libraries( opencv_demo ${
OpenCV_LIBS})
补充：
（1）cmake工具安装：sudo apt-get install cmake
或者，安装包安装，下载地址：https://cmake.org/files/
（2）kdevelop安装：sudo apt-get install kdevelop